Therapeutic or cosmetic? Patent strategies for dual-use innovations

In the pharmaceutical and cosmetic sectors, innovation often stems from discovering new applications for known compounds. In these situations, an innovator cannot patent the compound itself – since the compound itself is not novel. But they may still seek protection for its newly identified use. Critically, the nature of the new use (e.g., therapeutic or cosmetic) determines the type of patent claims that can be pursued in Europe.

Under the European Patent Convention (EPC), patents cannot be granted for methods of treating the human or animal body by surgery, therapy, or diagnostic practices.ⁱ However, the law allows patents to be granted for “substances or compositions for use in such methods.” As a result, when a known compound is found to have a new medical use, European patent law permits second medical use or purpose-limited product claims, such as:

“Compound X for use in treating disease Y.”

In contrast, these exclusions do not apply to cosmetic treatments. Therefore, when a compound is identified as having a new cosmetic use, method claims can be pursued at the European Patent Office (EPO), such as:

“Use of compound X in the cosmetic treatment of Y.”

On the face of it, the situation appears quite straightforward. However, difficulties can arise when both therapeutic and non-therapeutic uses of the compound (or composition) have been identified.

If the therapeutic and non-therapeutic effects of the compound can be clearly distinguished, the situation is relatively straightforward. The applicant can pursue method claims covering the non-therapeutic method and purpose-limited product claims covering the therapeutic use. However, in those situations where the non-therapeutic method is considered inseparably associated or inextricably linked with the therapeutic effect, securing patent protection before the EPO becomes more challenging.

Where the effects are inextricably linked

One of the earliest cases on this issue is T 290/86, which concerned a toothpaste composition containing a lanthanum salt. The patentee argued that the method of removing plaque from human teeth – essentially, cleaning the teeth and improving appearance – constituted a cosmetic use. However, the Board of Appeal determined that this method inevitably had a therapeutic effect, as it helped prevent caries and periodontal disease. As a result, the method fell under the exclusion from patentability, and the claim for a non-therapeutic use was deemed unallowable.

More recent case law has reinforced this principle, holding that when therapeutic and non-therapeutic effects are inseparably linked, merely limiting the claim to a "non-therapeutic use" or disclaiming the therapeutic aspect does not avoid the exclusion.

Where the effects are distinguishable

In T144/83, the EPO Board of Appeal considered whether a weight-loss method using an appetite suppressant should be classified as therapeutic or cosmetic. The key issue was that weight loss could serve both therapeutic purposes (treating obesity) and cosmetic purposes (enhancing appearance). The Board acknowledged that, in some cases, therapeutic and non-therapeutic uses can be adjoined “without a sharp distinction”, meaning that it could be difficult to distinguish between them.

However, in this case, the applicant’s claim specified weight loss "until a cosmetically beneficial result is achieved," without referring to obesity treatment. As a result, the Board ruled that the claim was limited to a cosmetic purpose, the exclusion under Article 53(c) EPC did not apply, and the patent was granted.

Another relevant case, T1916/19, concerned a composition with antimicrobial effects.ⁱⁱ The Examining Division at the EPO initially rejected the application, arguing that “an antimicrobial effect” would inherently provide a prophylactic treatment, since skin disinfection will always remove pathogenic bacteria. However, upon appeal, the Board held that a non-therapeutic use was also allowable.

The Board reasoned that there were some realisations of the method that were not therapeutic – removal of bacteria from healthy skin is not necessarily prophylactic, as the mere presence of pathogenic bacteria does not always lead to disease. They also recognised that the removal of non-pathogenic bacteria (e.g., such as those causing unpleasant body odour) was a cosmetic, rather than therapeutic, application.

As a result, the patent proceeded to grant with both a non-therapeutic method claim and a purpose-limited product claim covering the therapeutic useⁱⁱⁱ – offering the patentee full coverage over the various uses of their product.

Weight loss drugs

The distinction between therapeutic and cosmetic uses is particularly relevant in industries where actives have multiple effects, such as dermatology, oral care, and, more recently, weight management. A prime example of this is semaglutide. Semaglutide is a glucagon-like peptide-1 receptor agonist more commonly referred to by its brand name Ozempic. This active was originally identified as a treatment for type 2 diabetes, but it has gained global attention for its ability to promote weight loss.

Semaglutide is covered by numerous patent families, but we highlight one example below. In the original application,^iv the claims broadly referred to methods for preventing or treating a number of medical conditions (including type 2 diabetes, hyperglycaemia, impaired glucose tolerance, or non-insulin dependent diabetes, and obesity). The original claims also referred to methods of reducing body weight, reducing food intake, or inducing satiety.

During prosecution of the European counterpart in this family, the Examiner objected that claims directed to reducing body weight/food intake, or to inducing satiety, were not therapeutic methods representing a disease to be treated, but rather modes of action related to treating obesity. In response, the applicant limited the claim to the product for use in the prevention or treatment of obesity (a therapeutic use).^v In this family at least, it does not seem that the applicant has yet attempted to pursue a method claim directed to the reduction of body weight to provide coverage over this non-therapeutic use. Given case law, particularly T144/83, if the applicant wished to secure protection for a cosmetic weight-loss method, they would likely need to explicitly disclaim therapeutic use – i.e., obesity treatment – or frame the weight loss as purely cosmetic.

In contrast to the approach taken by the EPO, methods of treatment are allowable in the US. One US case in this same family did grant with claims broadly directed to “a method for reducing body weight…”.^vi

Given the commercial success of semaglutide, it is unsurprising that this patent family has faced legal challenges. The patentee, Novo Nordisk, recently settled a US patent lawsuit concerning semaglutide, and the EP patent is currently under appeal following revocation during opposition proceedings. Nevertheless, this family offers some useful insights into patent claiming strategies for weight loss drugs across the US and Europe.

Conclusions

These patent law nuances are highly relevant not only to cosmetic innovations, but also to the emerging fields of functional foods and nutraceuticals – where a non-therapeutic use may lie very close to a therapeutic (e.g., prophylactic) use. While it is possible to secure patent protection at the EPO for such inventions, careful drafting is essential to ease later prosecution of the patent.

For compounds with both therapeutic and non-therapeutic uses, these uses should be clearly distinguished and listed separately in the application to avoid overlap. One useful strategy is to define separate user groups – for example:

• A cosmetic use could specify a healthy subject.
• A therapeutic use could specify a subject suffering from a specific pathological condition.

Additionally, separate experimental data should ideally be included to support each use – for example, one demonstrating cosmetic effects and another proving therapeutic benefits. Taking these steps can significantly strengthen a patent application and improve its chances of success.

About the author

Mairi Rudkin, a partner at Marks & Clerk, handles a diverse range of chemical subject matter, including medicinal chemistry, formulation chemistry, polymers, and sustainable chemistry. She specialises in small molecule pharmaceuticals and has particular experience in controlled release drug delivery and the therapeutic areas of reproductive health, oncology, and infectious diseases.